The ego is like the rose and also like the thorns which surround the rose. It takes the place of the thorns when it is not cultivated, and it becomes a rose when it is refined. And the way to make it refined is to humble oneself and to crush one's desires. It is by the process of crucifixion that a person refines the ego. It is a hard grain, and it must be ground till it becomes a fine powder, out of which a paste is made.